#include "stdafx.h"
#include "code/sha1engine.hpp"
#include "platform.hpp"

#ifdef JH_ARCH_LITTLE_ENDIAN
#define SHA1_BYTE_REVERSE(x, y) byteReverse(x, y)
#else
#define SHA1_BYTE_REVERSE(x, y)
#endif

namespace JHCPP
{
	namespace code
	{
		CSHA1Engine::CSHA1Engine()
		{
			m_digest.reserve(16);
			reset();
		}

		CSHA1Engine::~CSHA1Engine()
		{
			reset();
		}

		unsigned CSHA1Engine::digestLength() const
		{
			return DIGEST_SIZE;
		}

		void CSHA1Engine::reset()
		{
			m_context.digest[0] = 0x67452301L;
			m_context.digest[1] = 0xEFCDAB89L;
			m_context.digest[2] = 0x98BADCFEL;
			m_context.digest[3] = 0x10325476L;
			m_context.digest[4] = 0xC3D2E1F0L;
			m_context.countLo   = 0;
			m_context.countHi   = 0;
			m_context.slop      = 0;
			std::memset(m_context.data, 0, sizeof(m_context.data));
		}

		const CDigestEngine::Digest& CSHA1Engine::digest()
		{
			int count;
			UInt32 lowBitcount  = m_context.countLo;
			UInt32 highBitcount = m_context.countHi;

			/* Compute number of bytes mod 64 */
			count = (int) ((m_context.countLo >> 3) & 0x3F);

			/* Set the first char of padding to 0x80.  This is safe since there is
			always at least one byte free */
			((BYTE*) m_context.data)[count++] = 0x80;

			/* Pad out to 56 mod 64 */
			if (count > 56)
			{
				/* Two lots of padding:  Pad the first block to 64 bytes */
				std::memset((BYTE*) &m_context.data + count, 0, 64 - count);
				SHA1_BYTE_REVERSE(m_context.data, BLOCK_SIZE);
				transform();

				/* Now fill the next block with 56 bytes */
				std::memset(&m_context.data, 0, 56);
			}
			else
			{
				/* Pad block to 56 bytes */
				std::memset((BYTE*) &m_context.data + count, 0, 56 - count);
			}
			SHA1_BYTE_REVERSE(m_context.data, BLOCK_SIZE);

			/* Append length in bits and transform */
			m_context.data[14] = highBitcount;
			m_context.data[15] = lowBitcount;

			transform();
			SHA1_BYTE_REVERSE(m_context.data, DIGEST_SIZE);

			unsigned char hash[DIGEST_SIZE];
			for (count = 0; count < DIGEST_SIZE; count++)
				hash[count] = (BYTE) ((m_context.digest[count>>2]) >> (8*(3-(count & 0x3)))) & 0xff;
			m_digest.clear();
			m_digest.insert(m_digest.begin(), hash, hash + DIGEST_SIZE);
			reset();
			return m_digest;
		}

		void CSHA1Engine::updateImpl(const void* data, unsigned length)
		{
			const BYTE* buffer = (const BYTE*) data;
			BYTE* db = (BYTE*) &m_context.data[0];

			/* Update bitcount */
			if ((m_context.countLo + ((UInt32) length << 3)) < m_context.countLo)
				m_context.countHi++; /* Carry from low to high bitCount */
			m_context.countLo += ((UInt32) length << 3);
			m_context.countHi += ((UInt32 ) length >> 29);

			/* Process data in BLOCK_SIZE chunks */
			while (length-- > 0)
			{
				db[m_context.slop++] = *(buffer++);
				if (m_context.slop == BLOCK_SIZE)
				{ 
					/* transform this one block */
					SHA1_BYTE_REVERSE(m_context.data, BLOCK_SIZE);
					transform();
					m_context.slop = 0 ;	/* no slop left */
				}
			}
		}



		/* The SHA f()-functions */
		#define f1(x,y,z)   ( ( x & y ) | ( ~x & z ) )              /* Rounds  0-19 */
		#define f2(x,y,z)   ( x ^ y ^ z )                           /* Rounds 20-39 */
		#define f3(x,y,z)   ( ( x & y ) | ( x & z ) | ( y & z ) )   /* Rounds 40-59 */
		#define f4(x,y,z)   ( x ^ y ^ z )                           /* Rounds 60-79 */

		/* The SHA Mysterious Constants */
		#define K1  0x5A827999L     /* Rounds  0-19 */
		#define K2  0x6ED9EBA1L     /* Rounds 20-39 */
		#define K3  0x8F1BBCDCL     /* Rounds 40-59 */
		#define K4  0xCA62C1D6L     /* Rounds 60-79 */

		/* 32-bit rotate - kludged with shifts */
		typedef UInt32 UL;	/* to save space */

		#define S(n,X)  ( ( ((UL)X) << n ) | ( ((UL)X) >> ( 32 - n ) ) )

		/* The initial expanding function */
		#define expand(count)   W[ count ] = S(1,(W[ count - 3 ] ^ W[ count - 8 ] ^ W[ count - 14 ] ^ W[ count - 16 ]))	/* to make this SHA-1 */

		/* The four SHA sub-rounds */
		#define subRound1(count)    \
			{ \
			temp = S( 5, A ) + f1( B, C, D ) + E + W[ count ] + K1; \
			E = D; \
			D = C; \
			C = S( 30, B ); \
			B = A; \
			A = temp; \
			}

		#define subRound2(count)    \
			{ \
			temp = S( 5, A ) + f2( B, C, D ) + E + W[ count ] + K2; \
			E = D; \
			D = C; \
			C = S( 30, B ); \
			B = A; \
			A = temp; \
			}

		#define subRound3(count)    \
			{ \
			temp = S( 5, A ) + f3( B, C, D ) + E + W[ count ] + K3; \
			E = D; \
			D = C; \
			C = S( 30, B ); \
			B = A; \
			A = temp; \
			}

		#define subRound4(count)    \
			{ \
			temp = S( 5, A ) + f4( B, C, D ) + E + W[ count ] + K4; \
			E = D; \
			D = C; \
			C = S( 30, B ); \
			B = A; \
			A = temp; \
			}

		void CSHA1Engine::transform()
		{
			UInt32 W[80];
			UInt32 temp;
			UInt32 A, B, C, D, E;
			int i;

			/* Step A.  Copy the data buffer into the local work buffer */
			for( i = 0; i < 16; i++ )
				W[ i ] = m_context.data[ i ];

			/* Step B.  Expand the 16 words into 64 temporary data words */
			expand( 16 ); expand( 17 ); expand( 18 ); expand( 19 ); expand( 20 );
			expand( 21 ); expand( 22 ); expand( 23 ); expand( 24 ); expand( 25 );
			expand( 26 ); expand( 27 ); expand( 28 ); expand( 29 ); expand( 30 );
			expand( 31 ); expand( 32 ); expand( 33 ); expand( 34 ); expand( 35 );
			expand( 36 ); expand( 37 ); expand( 38 ); expand( 39 ); expand( 40 );
			expand( 41 ); expand( 42 ); expand( 43 ); expand( 44 ); expand( 45 );
			expand( 46 ); expand( 47 ); expand( 48 ); expand( 49 ); expand( 50 );
			expand( 51 ); expand( 52 ); expand( 53 ); expand( 54 ); expand( 55 );
			expand( 56 ); expand( 57 ); expand( 58 ); expand( 59 ); expand( 60 );
			expand( 61 ); expand( 62 ); expand( 63 ); expand( 64 ); expand( 65 );
			expand( 66 ); expand( 67 ); expand( 68 ); expand( 69 ); expand( 70 );
			expand( 71 ); expand( 72 ); expand( 73 ); expand( 74 ); expand( 75 );
			expand( 76 ); expand( 77 ); expand( 78 ); expand( 79 );

			/* Step C.  Set up first buffer */
			A = m_context.digest[ 0 ];
			B = m_context.digest[ 1 ];
			C = m_context.digest[ 2 ];
			D = m_context.digest[ 3 ];
			E = m_context.digest[ 4 ];

			/* Step D.  Serious mangling, divided into four sub-rounds */
			subRound1( 0 ); subRound1( 1 ); subRound1( 2 ); subRound1( 3 );
			subRound1( 4 ); subRound1( 5 ); subRound1( 6 ); subRound1( 7 );
			subRound1( 8 ); subRound1( 9 ); subRound1( 10 ); subRound1( 11 );
			subRound1( 12 ); subRound1( 13 ); subRound1( 14 ); subRound1( 15 );
			subRound1( 16 ); subRound1( 17 ); subRound1( 18 ); subRound1( 19 );
			subRound2( 20 ); subRound2( 21 ); subRound2( 22 ); subRound2( 23 );
			subRound2( 24 ); subRound2( 25 ); subRound2( 26 ); subRound2( 27 );
			subRound2( 28 ); subRound2( 29 ); subRound2( 30 ); subRound2( 31 );
			subRound2( 32 ); subRound2( 33 ); subRound2( 34 ); subRound2( 35 );
			subRound2( 36 ); subRound2( 37 ); subRound2( 38 ); subRound2( 39 );
			subRound3( 40 ); subRound3( 41 ); subRound3( 42 ); subRound3( 43 );
			subRound3( 44 ); subRound3( 45 ); subRound3( 46 ); subRound3( 47 );
			subRound3( 48 ); subRound3( 49 ); subRound3( 50 ); subRound3( 51 );
			subRound3( 52 ); subRound3( 53 ); subRound3( 54 ); subRound3( 55 );
			subRound3( 56 ); subRound3( 57 ); subRound3( 58 ); subRound3( 59 );
			subRound4( 60 ); subRound4( 61 ); subRound4( 62 ); subRound4( 63 );
			subRound4( 64 ); subRound4( 65 ); subRound4( 66 ); subRound4( 67 );
			subRound4( 68 ); subRound4( 69 ); subRound4( 70 ); subRound4( 71 );
			subRound4( 72 ); subRound4( 73 ); subRound4( 74 ); subRound4( 75 );
			subRound4( 76 ); subRound4( 77 ); subRound4( 78 ); subRound4( 79 );

			/* Step E.  Build message digest */
			m_context.digest[ 0 ] += A;
			m_context.digest[ 1 ] += B;
			m_context.digest[ 2 ] += C;
			m_context.digest[ 3 ] += D;
			m_context.digest[ 4 ] += E;
		}

		void CSHA1Engine::byteReverse(UInt32* buffer, int byteCount)
		{
		#ifdef JH_ARCH_LITTLE_ENDIAN
			byteCount /= sizeof(UInt32);
			for(int count = 0; count < byteCount; count++)
			{
				UInt32 value = (buffer[ count ] << 16) | (buffer[ count ] >> 16);
				buffer[count] = ((value & 0xFF00FF00L) >> 8) | ((value & 0x00FF00FFL) << 8);
			}
		#endif // JH_ARCH_LITTLE_ENDIAN
		}
	}//end of namespace code
}//end of namespace JHCPP
